1. Field of the Invention
The present invention relates to packages for prosthetic devices, and more particularly a package for supporting a hip stem/hip prosthesis wherein a cassette having half portions supports the prosthesis at least around the proximal end thereof so that modular pads and modular distal sleeves can be assembled thereto while supported by the packages, prior to hip stem surgery.
2. General Background
There are a number of hip prosthesis devices that are commercially available which use a configuration that includes a lower stem which is generally cylindrical, a larger proximal end portion that includes anterior and posterior surfaces, and also a neck region to which an acetabular ball is affixed.
There are commercially available modular hip implant systems that provide proximal modules and distal modules. Because of the irregular shape of such hip implants and of the protruding modular parts which are to be added (such as modular pads and distal sleeves), complete assembly on a surgical table and during surgery can be very difficult. Another problem is that sterility must be maintained during installation of modular parts and removal of the implant from its package during surgery.
There are four commercially modular hip systems known to the Applicant, each of which addresses this problem in a different manner.
The Infinity hip system from Dow Corning Wright uses a vise to clamp the stem in place while the proximal module is applied with a mallet. This vise is cumbersome and could possibly cause damage to the stem. This implant system does not use a distal sleeve.
The Omni-Flex hip from Osteonics has a distal sleeve which is applied by laying the stem end up on the proximal end and pounding the distal sleeve in place with a mallet. This method can potentially cause problems because it allows the trunnion to rest on the table where it can possibly be damaged. Also the hip stem could possibly be knocked off the table during this installation, damaging the hip and compromising sterility.
The S-ROM Hip, from Joint Medical Products, has a proximal module which is placed in the femur first followed by the stem which is tapped into place at the proper orientation. This stem is assembled in the femur as opposed to preassembly.
The APR II, from Intermedics, has an open ended distal sleeve which is applied by using an impactor which is struck with a mallet.
An example of a modular hip prosthesis system can be seen in U.S. Pat. No. 4,995,883, entitled "Modular Hip Prosthesis", issued Feb. 26, 1991, and assigned to the assignee of this application, Smith & Nephew Richards Inc.
There are some patented constructions for packages and package assemblies that have been patented. As an example, U.S. Pat. No. 4,921,096, issued to Taut, Inc. describes a package assembly for a pointed surgical instrument. One part of the package comprises a clamshell-type portion which is openable so that the non-pointed end of the instrument can be grasped and the instrument removed or replaced in the package without touching the pointed end. The clamshell portion may be open or closed as required. The package is in two parts which are hinged together. One part cannot be opened and encloses the sharp point. The other part has the clamshell-type opening whereby when opened the non-sharp end of the product may be grasped to remove it from the package. After use, the product may be reintroduced into the package, the clamshell opening is closed again and the package may be disposed of.
U.S. Pat. No. 4,872,551 describes a clamshell blister pack for pliers wherein the head of the pliers is held in the pack and the handles can be manipulated by the customer. The package in the '551 patent includes a pair of opposing mirror-image panels having recesses and joined along a common lower end to form a base portion. The base portion is provided with a pair of openings for accommodating the handles of the pliers. The head of the pliers is held in the package but the handles protrude from the base of the package and can be manipulated to a specified extent by the customer prior to purchase without opening the package.